Category: Linux Game Development

The last time I wrote about Stop That Hero! development was in July. Here’s a quick summary of the work I’ve done since then:

Fixed memory bugs

I fixed a number of issues in July, specifically with weird corruption issues that seemed to result from the use of std::vector<bool> which is apparently not a real vector of boolean values. I was easily able to discover where memory leaks were occurring with Valgrind.

Recently, I ran into a bizarre unit test failure when adding code to a module that had nothing to do with the unit test, and I discovered that I had introduced a bunch of memory leaks that were finally manifesting in such issues. It wasn’t hard to fix since I once again was able to use Valgrind, but it was tedious work. A lot of it was fixing dumb mistakes, too. I have no idea why I thought I could get away with the code I wrote when I wrote it.

Unless there are corruption problems, memory bugs are not usually a big deal during development. Still, it would be nice if I used tools that made it easier to avoid the problems in the first place. I use UnitTest++, but these memory leak issues would have been caught had I used a tool such as CPPUTest which fails tests if memory leaks.

Added more minions, entities, and projectiles

Once I made combat revolve around projectiles, I added fireball-launching dragons and warlocks. Warlocks will eventually have a magic spell they cast, but they launch fireballs because that was the only projectile I had at the time.

Recently, I added new heroes. Archers shoot arrows, and wizards cast lightning bolts. I eventually want to add villagers and knights and get rid of the generic Hero character.

Optimized rendering

I’ve had the same update/rendering code for a long time, and on a whim, I added some logging to my game to find out why I wasn’t able to get 60 FPS even though I didn’t think I was doing much.

It turned out, I wasn’t doing much. All of my code ran within a millisecond, but the actual SDL call that blits to the window took between 30-50 ms to run! The good news is that my own code isn’t slowing me down, but mathematically it’s impossible that SDL MUST render this slow since so many other SDL games run much faster. So I looked to find out what other people did to make it work.

Here’s the code I was using to set the video mode:
m_screen = sdlInstance->SDL_SetVideoMode(m_x, m_y, m_bitDepth, SDL_DOUBLEBUF);

And here’s a much faster version based on a thead at Ubuntu Forums that I apparently did not bookmark:
m_screen = sdlInstance->SDL_SetVideoMode(m_x, m_y, m_bitDepth, SDL_SWSURFACE | SDL_ASYNCBLIT | SDL_DOUBLEBUF | SDL_ANYFORMAT | SDL_SRCALPHA);

So I went from 30-50 ms to 8 ms. The game runs so much more smoothly now, and it didn’t take a lot of work at all.

Switched away from pie menu

Pie menus are great for usability, but only if you can guarantee that the menu can be displayed in its entirety around the mouse cursor. Since one goal with “Stop That Hero!” was to make the interface as simple as possible, I didn’t want a scrolling world. The entire world fits on the screen at once. To use pie menus, I’d have to reduce the world size to provide a border all so that buttons could fit on the screen if a tower was selected near the edges.

So I removed the pie menu and went back to a traditional UI at the top of the screen.

Added resources and minion costs

Before, I was adding minions to the game whenever I wanted. Now there are resource costs, and it takes time to summon a minion from a tower. The player starts with a base set of resources, and the current system adds 1 resource every second. It’s simple, and it works. I can experiment with resource mechanics, such as adding rewards for killing heroes or if certain minions collect items and bring them back to the player’s castle, but the basic system is in place.

Made object creation more generic/data driven

I initially tried to make the game as quickly as possible, so instead of trying to genericize object creation, I created a bunch of separate commands: CreateHeroCommand, CreateDragonCommand, CreateOrcCommand, etc.

While it worked, it was also very limiting. Each time I added a new type of entity or in-game object, I had to create a new command. Maybe that’s fine if I know what entities and objects I want to create up front, but it limits the design. Maybe I want to make weak squires, regular soldiers, and strong knights as variations on each other. The effort to write the code for the separate creation commands would be tedious and slow.

So I replaced all of those CreateXYZCommands with CreateObjectFromTemplate. Instead of having coded commands to create an orc, I create a template called Orc, which defines components and data that an orc would have. CreateObjectFromTemplate(“Orc”) then creates the components with the correct data, and an orc appears in the game world.

Templates can be created and changed much more easily than hardcoded commands, which means adding and tweaking minions, heroes, and other in-game objects is easier, which means game design and balancing is easier. It also allows me to data-drive the game a lot more, which means more interesting entities and game situations.

Added timer-based summoning queues

Both heroes and minions take time to appear. Minions are summoned and there is a summoning bar that lets you know how finished the current summon is. By using the same summoning queue code, I now have a Village which pops out heroes over time.

Timers seemed like a special case of general triggers. It would be nice to have dwarves pop out of caves if any entities come near or have other similar scripting in the game, but my initial attempt at general triggers might have been trying to do too much. Maybe for another game.

What’s Next?

The game is still silent, so eventually I would like to add some sound effects and music. Animations and special effects would really punch up the visuals, which need a consistent art direction. It’s all functional programmer art and will get replaced.

But the biggest thing left to do is improve the AI. Dragons can attack from distance, yet they still try to run up to the heroes the way melee fighters do. Also, entities tend to bunch up. 10 orcs attacking a hero tend to look like a single orc attacking the hero, and it is hard to see what’s happening.

My initial attempt at solving these problems resulted in unacceptable slowness last week, but I’ve identified what’s going on and think I have a fix for it.

But hey, this is AI work. I already know I can’t expect that I’ll figure it out in a matter of hours or days. There’s going to be a lot of changes, tweaks, and fixes until it looks right.

And besides game development work, there’s the work of marketing and selling the game. There’s a “Stop That Hero!” Facebook page, and I just sent out a newsletter to my list announcing the upcoming release. I’m hoping to get a pre-alpha release out soon.

It’s really exciting when I add a feature to Stop That Hero! that I can actually show to someone, and in the last week or so, I’ve added two.

First, slime monsters now leave behind a slime trail. If the Hero steps in the slime trail, he is slowed down temporarily. The slime trail and the slow effect both wear off eventually.

Second, to actually take advantage of the slime trail’s slowing effect, I added projectile weapons. The idea is that the player will strategically send out slimes ahead of stone-throwing orcs or fireball-launching dragons. Their weapons should be more effective against a slowed Hero since they have more time to attack more often.

Once I changed attacks in the combat system to be projectiles, a quick test was to take an existing entity in the game and change its weapon configuration. Since I only had Heroes and slimes, I gave slimes the ability to throw a projectile at the Hero. Instead of attacking from one tile away, they can now attack from 10 tiles away. And to give the projectile an image, I used an existing sprite rather than spend time making something that looks good.

So for this test, it is the Hero versus treasure chest-throwing slimes!

The development video below is a demonstration of the results. Please excuse the lame art. I’m focusing more on the game mechanics/dynamics and less on the aesthetics for now.

I’m pleased to say that it only takes a handful of slimes to defeat the Hero instead of requiring a small army. While it means that my test worked as expected, it also means I’ll need to make some of the Heroes more powerful once I create some orcs or dragons, who should be stronger than the slimes.

After returning from Europe, I spent over a week dealing with being sick. Even though I couldn’t get back to work right away, I was able to read through all of the advice I received on my post on the importance of speed, and I really appreciate all of the feedback. Thanks, everyone!

In that post, I expressed frustration with how slow my game development has been, especially with Stop That Hero!. I wondered if the project was too much for me at my current skill level, and if I needed to step back and try lifting lighter weights, so to speak. I know some game developers leverage a library of personal code that they have written and updated over the course of years. Others leverage existing engines.

While I have some boilerplate code, it’s not nearly as comprehensive as I would like it to be, and the stuff I do have isn’t always as easy to work with as it should. As I said in that post, 2D engines for GNU/Linux, my development platform, by and large do not exist, so I find I have to write a lot myself. If I had more to leverage, I’m sure development of STH! or any other game would be a lot faster since I wouldn’t have to stop and implement scaffolding technology to support a feature every time. It would already exist.

The advice I received fell into a few camps:

1. Muscle through and get the game finished. Your tech will be ideal and perfect for YOUR needs.
2. Stop targeting GNU/Linux and desktops in general as platforms, and focus on more “marketable” platforms.
3. Stop working in C++, and use Flash/Unity/higher-level programming language/engine instead.
4. Break your project down into smaller projects so you can have finished games and build your needed tech.
5. Stop writing your own tech from scratch, and leverage the hell out of libraries/engines/existing source.
6. Stop worrying about writing “good” code. Hack something together and get it done faster!

I didn’t know whose advice to ignore first! B-) Seriously, though, let me clarify some things about what I’m trying to do.

First, I am not making games just for GNU/Linux, and I never said I would, yet this seems to be a common assumption about my business plan. I am not locking myself to only one platform. My original plan all along was to release games for GNU/Linux, Windows, and Mac. It turns out that ports to mobile platforms, which are a huge opportunity these days, would also be fairly easy, so I went from following supposedly dying tech to being relevant again.

Second, I’m using C++ because it is what I know, and my choice was to make a game or spend time learning a new language to make a game. I chose to go with what I already know, even if it supposedly limits me, because I wanted to start running right away instead of figuring out how to put on my shoes. I can always use the next project to learn a new language if I want to, and switching languages on this project would be way too disruptive and set me back way too much.

Third, because my development platform is GNU/Linux, which makes targeting GNU/Linux dead-simple and a no-brainer, it means that engines like Unity are not options for me. I might be limiting myself in terms of access to premium development tools such as Photoshop and Adobe Flash, but I have been using GNU/Linux exclusively as my main desktop environment for a long time, and I’m not about to start booting into Windows just because most everyone else does. I’ve had to find non-proprietary alternatives for a lot of applications and tools, and I’m doing it for game development as well.

All that said, I think everyone had great advice, whether it was about my tech or my business plan or my development process. Without sales, my savings account is going to get smaller and smaller, and my biggest concern was where I should be focusing my time.

My choices:

• I could continue to work on Stop That Hero!. I have been discovering how much more complex it is and how much longer it is going to take to finish it, and there’s a worry that by the time it is done, I’ll be out of savings. To make it worse, I’m very much aware that I can’t expect sales to take off just because the game is released. Sales is going to to be a lot of work, and I might not make enough to cover my expenses early on, forcing me to spend time and effort making money in other ways, which takes away from my business. And I’ll admit that I do not know what the reception of this game will be once it hits a real audience, although I do plan to get feedback from play testers once I have something I feel comfortable showing to people, which should help. Still, it might be an unsellable flop that can’t be salvaged no matter what I do. That’s a lot of pressure on this one game.
• Put STH! on the backburner and work on something smaller. My intention was to work on multiple small games over the course of the year. I’ve since learned more about my capabilities as a game developer and the limitations of my existing tools and tech. Essentially, STH! was not as “small” a game as I originally thought. STH! was meant to be a one-month game project in the first place. Since the schedule has slipped so far, perhaps it is best to cut my losses or at least put the game on hold and work on something I can accomplish in a matter of weeks. I have a couple of Ludum Dare projects that could be candidates for simple games. The diversified portfolio I could create in a matter of months could help reduce risk. If one game doesn’t do well, I’d have another one on the way shortly, and cross-selling might help improve sales. On the other hand, what kind of sales can I expect on a bunch of quickly-produced games that must compete with all of the free and low-priced casual games being produced every day, as opposed to focusing my efforts on my current project? Also, I run the risk of having two unfinished projects since it is possible that a lot of the problems I’ve encountered with STH! could crop up in another project anyway.

If finishing STH! would take two years, and my savings will only hold out for three months, I’d do best by switching to a smaller, faster project in the hopes that I can make at least some income. On the other hand, the race to the bottom in the pricing of games doesn’t provide me with a lot of encouragement to produce small, disposable games. Perhaps the fact that STH! is a bigger project means that the finished product can be something that a fan base could build around.

Since STH! is not a two year project and I expect to finish it before I have to worry about my savings disappearing, I’ve decided to continue working on it. My goal is to get it commercially ready to sell in June.

I did not have a playable game to release yet, but I looked at the remaining features to implement and various ideas I wanted to try, and I started pushing a bunch to Version 2.0. I spent a good chunk of the remainder of April in a self-imposed crunch. I ignored my project planning system, ignored writing for the blog (which explains the lack of posts in the previous month before Ludum Dare), and dedicated as much of my time as I could to making a friends-and-family playable game.

By friends-and-family playable, I mean I wanted to implement enough of Stop That Hero! so that I can hand it to my fiancée or a friend and say, “Here, play it with the understanding that this is an early Alpha version. The graphics suck, there’s no sound, and the game play is raw.”

While that Alpha build isn’t ready yet, I will say that April has been a very productive month, especially considering that I was only able to do all of the work in the final couple of weeks. And since recovering from Ludum Dare #20, I’ve started off May with some quality development time as well.

I’m seeing this project through, and I’m confident Stop That Hero! will be a great game.